Radial piston devices (either pumps or motors) are often used in aerospace hydraulic applications and are characterized by a rotor rotatably engaged with a pintle. The rotor has a number of radially oriented cylinders disposed around the rotor and supports a number of pistons in the cylinders. A head of each piston contacts an outer thrust ring that is not axially aligned with the rotor. A stroke of each piston is determined by the eccentricity of the thrust ring with respect to the rotor. When the device is in a pump configuration, the rotor can be rotated by operation of a drive shaft associated with the rotor. The rotating rotor draws hydraulic fluid into the pintle and forces the fluid outward into a first set of the cylinders so that the pistons are displaced outwardly within the first set of the cylinders. As the rotor further rotates around the pintle, the first set of the cylinders becomes in fluid communication with the outlet of the device and the thrust ring pushes back the pistons inwardly within the first set of the cylinders. As a result, the fluid drawn into the first set of the cylinders is displaced into the outlet of the device through the pintle.
Radial piston devices include various passages that form a variable orifice between pumping elements and inlet and outlet ports. At least some of the passages are configured to alternatingly open and closed as the rotor rotates to pump hydraulic fluid. The design of the passages can modify the timing at which the passages are open and closed in the operation of the devices. Suboptimal timing design can increase a chance of pressure pulsations and/or cavitation, thereby decreasing efficiency of the devices.